To understand the concept of nation-building, one needs to have some definition of what a nation is. Early conceptions of nation defined it as a group or race of people who shared history, traditions, and culture, sometimes religion, and usually language.
Thus the United Kingdom comprises four nations, the English, Irish, Scottish, and Welsh. The people of a nation generally share a common national identity, and part of nation-building is the building of that common identity.
Some distinguish between an ethnic nation, based in (the social construction of) race or ethnicity, and a civic nation, based in common identity and loyalty to a set of political ideas and institutions, and the linkage of citizenship to nationality.
Today the word nation is often used synonymously with state, as in the United Nations.
But a state is more properly the governmental apparatus by which a nation rules itself. Max Weber provided the classic definition of the state:
Today, however, we have to say that a state is a human community that (successfully) claims the monopoly of the legitimate use of physical force within a given territory. Note that “territory” is one of the characteristics of the state. Specifically, at the present time, the right to use physical force is ascribed to other institutions or to individuals only to the extent to which the state permits it.
In approaching the question of nation-building, and in particular its relationship to state-building, it is important to keep in mind that this definition specifies the legitimate use of force.
If nation-building in the 20th century is to be successful, it may want to return to look at some of its early theorists.
The importance of democratic values, of the civic culture and civil society that develop and sustain them, the importance of increasing social, political, and economic equality, and of human development, rather than just economic development or state-building, are key in any successful strategy for long-term democratic nation-building.
Nation-building is more than just state-building.
To be a sustainable force for peacebuilding, it must incorporate more than just the Western appendages of democracy.
Voting systems and free market development and increasing the GNP per capita are not likely to bring stable peace.
 Weber, Max. “Politics as a Vocation,” in Gerth and Mills. From Max Weber. New York, 1946. 48.